Our goal is to eventually develop site-specific inhibitors of the HIV-1 protease. To that end we continued our investigations on the effect of heavy metals on protease activity. Also, other related areas on the biochemistry of the HIV-1 protease were investigated. We found that peptide copper chelates as well as nonpeptidic copper complexes were able to strongly inhibit the protease activity similar to that of free copper. The chelates appeared to be working by delivering copper to the site of action in the protease. Data on the inhibition of the protease by copper in the presence of dithiothreitol indicated that it, too, may function as a copper chelate inhibitor. Therefore, we may be able to use delivery systems like these to specifically target the protease. An antibody was produced which recognized the HIV-1 protease on Western blots. This antibody will be used to further probe the mechanism of copper inhibition. It was also found that albumin could significantly stabilize protease activity and was useful in studies of the protease run under native gel filtration. Activity of the protease was recoverable under conditions where albumin was present in the running buffer or in the collection tubes. The HIV-1 protease is essential for the production of infectious virions from infected cells. A clear understanding of the biochemistry of the HIV-1 protease should allow for the development of novel inhibitors of this important target for the prevention of AIDS.